[PATCH] drm/amd/amdgpu: Fix GPU reset handling after WGR is triggered

[Nikola Petrovic]

I've identified a critical issue with the existing GPU reset mechanism that causes a BSOD on the Windows Hyper-V platform. The current function:

static void xgpu_nv_mailbox_flr_work(struct work_struct *work)  

incorrectly sets the AMDGPU_HOST_FLR flag if any engine is hanging. This approach wrongly assumes that the Host PF is always responsible for triggering FLR. However, a VF (VM-guest) can also cause a GPU hang, which results in an unsuccessful VM reset. This ultimately causes a FULL_ACCESS_TIMEOUT on the host side, leading to six attempts to retrigger a Whole Guest Reset (WGR), which results in a BSOD after five to six failed restarts.

Additionally, the current sequence sends a READY_TO_RESTART event and then requests FULL_ACCESS, which seems incorrect to me.

My fix addresses this problem by using REQ_GPU_RESET to initiate the necessary restart while appropriately handling the FULL ACCESS request. My implementation has successfully passed 100 loop tests, confirming its effectiveness.

Signed-off-by: Nikola Petrovic <nipetrov at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 7f354cd532dc..a2a436707200 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -5314,11 +5314,12 @@ static int amdgpu_device_reset_sriov(struct amdgpu_device *adev,
 	struct amdgpu_hive_info *hive = NULL;
 
 	if (test_bit(AMDGPU_HOST_FLR, &reset_context->flags)) {
+		r = amdgpu_virt_wait_reset(adev);
+		if (r)
+			return r;
 		if (!amdgpu_ras_get_fed_status(adev))
-			amdgpu_virt_ready_to_reset(adev);
-		amdgpu_virt_wait_reset(adev);
+			amdgpu_virt_reset_gpu(adev);
 		clear_bit(AMDGPU_HOST_FLR, &reset_context->flags);
-		r = amdgpu_virt_request_full_gpu(adev, true);
 	} else {
 		r = amdgpu_virt_reset_gpu(adev);
 	}
-- 
2.43.0